Confining homogeneous Ni0.5Co0.5Se2 nanoparticles in Ti3C2Tx MXene architectures for enhanced sodium storage performance

Transition metal selenides are regarded as potential sodium storage materials for their high theoretical capacity and superior electrical conductivity. However, unsatisfied cycle stability and rate capability, which is caused by its intrinsic structural instability and sluggish conversion reaction, greatly hinder the application. Herein, in-situ electrostatic attraction and selenization process are used to construct Ni 0.5 Co 0.5 Se 2 /Ti 3 C 2 T x composite, in which the homogeneous Ni 0.5 Co 0.5 Se 2 nanoparticles are anchored in the Ti 3 C 2 T x MXene architecture. Based on the unique confinement effect and strong chemical interface coupling, the volume expansion and aggregation of the Ni 0.5 Co 0.5 Se 2 /Ti 3 C 2 T x anode during the cycling process are effectively prevented. Furthermore, the evenly Ni 0.5 Co 0.5 Se 2 bimetallic selenides nanoparticles endow rapid charge transfer and redox kinetics due to shortened Na + diffusion distance and more accessible active sites. As a result, the as-prepared Ni 0.5 Co 0.5 Se 2 /Ti 3 C 2 T x anode exhibits long cycle stability over 1000 cycles at 2.0 A g −1 , pushing forward the construction of advanced conversion-type anode for high-performance sodium-ion batteries.